Governor for internal combustion engines



Sept. 25, 1934. ivi. HURST GovERNoR RoR INTERNAL coMBUsTloN ENGINESFiled May 29, 1950 2 Sheets-Shea?I l Sept. Z5, 1934. M. HuRsT GOVERNORFOR INTERNAL COMBUSTION ENGINES Filed May29, 1930 2 Sheets-Sheet 2 3 MNum?? @LLL MSA,

Fatente Sept. 25, i934 SES 1,974,851 GovERNoR Fon INTERNAL' coMnUs'rloNENGnvEs Max Hurst, Stuttgart, Germany, assigner to Robert Germany BoschAktiengesellschaft,

Stuttgart,

Application May 29, 1930, Serial No. 457,288

Germany November 23, 1929 13 Claims.

The present invention relates to governors forI internal combustionengines and is particularly applicable for the speed control of internalcombustion engines fedby fuel cil on the solid injection or airinjection systems.

In internal combustion engines, more particularly in the case of airinjection and solid injection Diesel motors, it is usual to use agovernor, usually of the centrifugal type, for controlling the 1Qquantity of fuel supplied for combustion so that any desired speed cirevolution may be retained.

According to the present invention hydraulically operated means areprovided in the path of the fuel for regulating the supply of fuel tothe engine.

The invention is Amore particularly described with reference to theaccompanying drawings which show, in part sectional elevation, eightforms of constructions by way of example.

In the first form of construction according to Figure l a fuel nozzle 11is mounted in the cylinder cover- 10 of an engine. A pipe 12 connectsthe nozzle with a fuel feed pump 13. The piston or plunger 14 ofthispump is forced into the pump cylinder 16 by a cam 15 timed inaccordance with the engine cycle and thus forces the fuel, fed to thecylinder 16 from a fuel container 18 through a suction pipe 17, over anon-return valve 20 and through the pipe 12 to the nozzle 11,

the spring-loaded needle valve 19 of which opens the nozzle orifice at agiven pressure so that the fuel is sprayed into the engine cylinder.

In addition to the pump piston there is mounted in the pump body 13 asecond piston 21 which closes a channel 23 connecting the pressure pipe12 of the pump with' the suctionpipe 17 by means of a needle-like stop22 as long as the force exerted on the piston by a spring 24 is greaterthan the hydraulic pressure of the fuel operating upon it. The loadingof the spring 24 can be varied by an adjusting screw 25.

This first form of the invention operates as follows:-

During its suction or down stroke the piston 14 first produces a vacuumin the pump cylinder 16 untilthe end of the suction duct 17 isuncovered, when fuel flows into the pump cylinder. -As the piston movesfrom the outer or lower position shown, it begins, after the end of thesuction duct 17 is closed, to discharge through the valve 20 into thepressure pipe 12. As soon as a predetermined pressure is attained there,the nozzle needle is raised and the fuel begins to spray through thenozzle orifice into the combustion space of the en- F gine cylinder.Spraying of the fuel discharged by (Cl. 10S-42) the piston 14 can becontinued until a predetermined rate of fuel discharge is attained, andconsequently until a predetermined engine speed is reached without thepressure in the pump chamber and in the pressure pipe being increased to50 that pressure at which the piston 21 is moved and the valve 22consequently opened. As long as this state is continued, all the fueldischarged by the piston 14 is injected into the engine cylinder throughthe nozzle.

If the speed of the engine and consequently the discharge velocity ofthe piston 14 exceeds the predetermined value, then the, pressure in thepump chamber and in the pressure pipe increases so that the piston 21isv displaced against the 70 force of the springv 24 and the valve 22opened, whereby fuel can escape from the pressure pipe through the nowopen connection from this pipe into the suction pipe.

The whole of the fuel discharged by the piston 14 is now no longerinjected, thev amount being reduced by the fuel returned throughf'thevalve 22, whilst the proportion of the discharge return increases withthe engine speed. At a given engine speed therefore there is only somuch'fuel 80 discharged as is necessary to retain this speed. Theeffective discharge is thus automatically adjusted in accordance withthe tendency of the engine to increase its speed of rotation, and asshown the variation in the pressure difference between the two pressuresurfaces of the piston 21, dependent upon the rate of fuel discharge, isused for this purpose.

In order that the valve 22 after opening is not immediately closed againby the reduction in pressure caused by such opening, a throttle isprovided in the return flow channel 23 so that the effective pistonsurface is increased after movement. In the example shown this throttleconsists of an annulus formed between the wall of the return flowchannel 23 and a peg 26 mounted on the valve 22.

By alteringthe loading of the spring 24 by means of the screw 25 thespeed of the engine can be altered as can be easily seen, since thehydraulic pressure required to displace the valve 22 is varied. It istherefore possible to suitably adjust the engine speed simply byaltering the load on the member controlling the return ow channel. Thissimple means of adjustment is particularly valuable for vehicle engines.

In order to be able to stop the engine at any time it is only necessaryto relax the spring 24 so far that the valve 22 is opened under a lowerfluid pressure than the nozzle pressure whereby the fuel discharged bythe pump can flow back to the suction pipe through the valve 22.

The second form of construction shownV in Figure 2 differs from thefirst mainly in that the movable regulating member, piston 21, itselfcontrols the return flow channel 23 instead of the valve 22 provided inthe first example. Instead of a closed fluid injection nozzle, an opennozzle provided with a plurality of holes is used in the second example.The path of the regulating piston 21 is limited by a stop 27. The modeof operation is exactly similar to that of 'the first example.

If it is desired to shut off the engine in the construction according toFigure 2, it is only necessary to hold the pump piston 14 in its inneror raised position by means of a lever 28 in known manner, so that thepump ceases to work and therefore to discharge.

In the third form of construction according to Figure 3 amovable.regulating member 21 does not control a return flow passage asin the above described examples, but is here constructed as a piston fora storage chamber in which a portion of the fuel discharged by the pumpis temporarily stored. One side 'of the piston 21 is subject to thehydraulic pressure prevailing in the pump chamber 16 at any instantwhilst the other side is loaded by means of a compression spring 24.

The mode of operation is as follows:-

The more the engine speed and therewith the discharge velocity increase,the more increases also the pressure in the pump chamber during thedelivery stroke of the pump because, as in the examples above described,the time allowed for the discharge of the fuel through the injectionnozzle is reduced. The loading of the piston 21 which is variable bymeans of a screw 25 may be so adjusted that the piston 21 is retained inits initial position until any predetermined pressure is obtained in thepump chamber and therefore until any given speed of rotation of theengine is attained. If the engine speed rises above this limit then thepiston 21, due to the Iincrease in hydraulic pressure, recedes from itsstop-ring 27 during the pressure stroke of the pump piston and receivesor stores in the space thus made available a portion of the fueldischarged by the pump piston.

Towards the end of its pressure stroke the pump piston places the pumpchamber in communication with the suction pipe through a channel 29 andan annular groove 30. The piston 21 can now force the fuel taken up orstored during the previous part of the pressure stroke back into thesuction pipe through the channel 29 and grooves 30 so that the piston 21is again in its position of rest shown in the drawings, for thebeginning of the next pressure stroke. If the speed of the engine isincreased due to a reduction in the load thereon so that the pressure inthe pump chamber is increased then the quantity of fuel delivered to theengine will be correspondingly decreased to that required formaintaining the normal engine speed.

In order to reduce as far as possible any irregularity or hunting in theautomatic adjustment described above, provision must be made forobtaining adequate displacement of the piston 21 when the given maximumhydraulic pressure is reached. For this purpose the stop of the piston21 is so formed that the effective piston surface is enlarged as soon asit is displaced from its stop.

In the fourth form of construction according to Figure 4 thehydraulically operated movable shaft 31 influencing the regulation ofthe fuel injected, is firmly attached to a movable needle of the loadedvalve 20 and extends behind the valve 20 into the pressure pipe leadingto the engine. The shaft or piston 31 would shut off the fuel passage ifa channel were not provided which in the case illustrated is formed as ahelical screw groove 32 on the circumference of the shaft which allowsthe throttled passage of the fuel. The throttling of the fuel in thegroove 32 causes a fall in pressure, varying with the engine speed,between the end surfaces of the shaft 31 which is displaced against theresistance of a spring 35 when the pressure drop is attained.

This form of construction operates as follows:-

As soon as the suction and return flow chan` nels 33 have been closedduring the compression stroke of the pump piston 14 the valve 20 israised by fuel pressure and the fuel is driven into the chamber 34 infront of the shaft 31. When a given engine speed is reached thethrottling groove 32 does not allow the fuel to pass to the injectionnozzle as quickly as it is discharged into the chamber 34, so that thepiston-like shaft 31 is yraised against the pressure of the spring 35 inorder to increase the volume of the chamber 34 to provide accommodationfor the excess fuel. Towards the end of the pressure stroke, in the samemanner as in the preceding example, the

pump chamber 16 is connected to the suction side of the pump through thechannel 29 and the annular groove 30, whereby the spring 35 and the fuelpressure present above the shaft 31 force the valve 20 together with theshaft 31 downwardly into the position shown in Figure 4. The shaft inreturning thus forces fuel from the chamber 34 back into the pumpchamber. The pressure pipe above the shaft 31 is thus relieved of acertain amount of fuel and sometimes even partially emptied.

Before the beginning of the subsequent injection the pump `piston mustfirst force suiiicient fuel past the-valve 20 into the pressure pipe toreplace the fuel withdrawn at the end of the preceding injection. Thequantity of fuel to be replaced increases with increase in the lift ofthe adjusting member 31 and consequently with increase in fuel dischargevelocity. Thus, the amount of fuel delivered to the engine at eachinjection is only just sufhcient to maintain the desired engine speed.

In the fifth form of construction according to Figure 5 a movableregulating member' 21 is provided in the suction duct of the fuel pump.The regulating member 21 is formed as a piston valve controlling theeffective cross-sectional'area of the suction pipe 17, the front side ofthe piston valve being subjected to suction or negative pressure and theopposite side to atmospheric pressure.V A weak spring 24 tends tomaintain the piston valve 21 in the position shown where the effectivesuction cross-sectional area controlled by it is greatest. The fuelentering through pipe 17 passes through a boring 36 and a throttleorifice 37 to a continuation 17 of the suction pipe leading to thesuction valve 38 whence contrary to the other examples it flows duringthe whole suction stroke into the pump chamber 16, which is filled to agreater or lesser extent according to the suction velocity.

'I'he construction described operates as follows:-

As long as the motor does not run too quickly, the control piston 21 isAnot displaced. If the speed of the engine increases beyond a given limitthen the fall in pressure in the passage 17 causes longitudinal motionof the valve 21 during the suction stroke with the result that thethrottle opening at 36 is reduced or even closed. This reduction ofthethrottle opening 36 causes reduction in the quantity of fuel enteringthe pump chamber during the suction stroke, and therefore a reducedquantity of fuel injected into the engine.

In the example just described with reference to Figure 5 the lling ofthe pump chamber is regulated in contra-distinction to the previouscases in which an adjustable portion of the fuel sucked up during thesuctionstroke is returned or by-passed to the fuel supply.

In the sixth form of construction shown in `Figure 6 the quantity offuel discharged by a pump having a plurality of cylinders can beautomatically regulated by the hydraulic action of the fuel in onecylinder.

In the pump body 13 are provided several cylinders 1 6, 16' in whichpistons 14, 14' of the same type are moved by the cams 15, 15 mounted ona common shaft and displaced corresponding to the number of enginecylinders. The separate pumps have a common suction pipe 17. Into thepump cylinders open channels, 40, 41 which are connected by tap borings42, 43, 44 to the suction pipe 17, the fueldischarged by the pistonspassing over non-return valves 20, 20' into pressure pipes 12vleading tothe injection nozzles not shown.

On the ends of the pump pistons 14, 14' and projecting into thecylinders are steering sur-- faces which cover channels 39 and 40 for aportion of the piston stroke and which are bounded on one side by thefront vedge of the piston and on the other side by an oblique vedge 45.A groove 46 in each of the pistons connects the pump chambers 16, 16'with a recess 47 behind the oblique edge. By rotating the pistons bymeans of a toothed adjusting rod 48, the length of the steering surfacescovering the channels 39 and 40 may be varied. By this, the effectivedischarge quantity of each separate pump is altered since as soon as theinclined edge opens the channel 39, the fuel displaced by the uplwardlymoving piston is forced back from the pump chamber 16 through the groove46 and the recess 47 into the channel 39. The regulation of the quantitydischarged by displacing the adjusting rod isthe same in all theseparate ,L pumps.

For moving the adjusting rod 48 the fuelv discharge velocity, variablewith the engine speed, is used. The spring loaded non-return valve 20 isprovided with a piston-like guide shaft which is bored longitudinallyfor passage of the fuel. 'Ihe boring is throttled at one end 49 adjacentthe pump piston 16 and a radial branch 50 from the boring is adapted toregister with a channel 51 in the pump body when thevalve 20 has beenraised sufficiently. The vchannel 51 leads to a chamber 52 in which apiston 53 is fitted and a throttle bore 54 leads from the chamber 52 tothe channel 42 connected to the suction pipe.

An arm or projection on the end of the piston 53 is articulated to oneend of a lever 55, which is pivotally mounted at 56. The other end ofthe lever 55 is connected to the end of the adjusting rod 48, which isurged into the position shown by a spring 57.

The pump described operates as follows:-

vAs long as the engine does not run too quickly, the control mechanismis not operated. If the speed of rotation increases then the differencein the pressures acting on the spring-loaded valve 20 is also increasedbecause the throttle orifice 49 will no-t allow the fuel discharged bythe pump piston 14 to pass, in the reduced-time available without anincrease in pressure in the chamber 16. Thus the lift of the valve 20 isincreased with increasing engine speed until at a given speed thecross-bore 50 in the shaft.

Ainto the chamber 52, then the spring 57 begins to return the adjustingrod together with the pump piston and also the piston 53 to their formerpositions, so that the effective discharge quantity again increases. Thefuel forced out during the return of the piston 53 flows 01T through thethrottle boring 54 to the suction side of the pump.

In the seventh form of construction according to Figure 7 all the partsof the regulating arrangement are mounted in an intermediate housing,which is inserted anywhere in the pressure pipe leading to the injectionnozzle.

Inserted in a boring of this housing is a guiding member 60 receiving apiston-like Valve control member 59, and a closing nipple 61. A pressurespring 62, which on one side abuts against a collar 59' engaging withthe valve and on the other side against an adjusting spring plate 63,tends to retain the valve in the position shown.

Branching-from a longitudinal bore 64 in the control member 59 aretransverse borings 65 and 66. The boring 65 is connected in the positionof rest of the valve through a boring 67 in the guiding member 60 to thecontinuation of the pressure pipe leading to the injection nozzle whilstthe borings 66 are shut oli' in the position of rest. After a givenupward movement of the valve however the borings 66 connect thelongitudinal boring 64 with a transverse boring 68 in the guiding member60 which communicates through an outlet 69, and a pipe 70 with the fuelcontainer 18. A stop 71 limits the stroke of the regulating valve. Thelongitudinal boring 64 is throttled at its inlet endby a plug 73 havinga throttle orifice 72 forme therein.

The operation of the control mechanism is as followsz Up to a certainengine speed the throttle 'orifice 72 allows allv the fuel discharged bythe pump to pass through without sufficient increase of pressure arisingin the pipe 12 to\ raise the piston 59 against the pressure of thespring 62. If however the engine speed increases further, the throttleorifice 72 only allows the fuel discharged to pass through under anincreased pressure, which is able to overcome the counter forces actingon the controlling piston 59, and to raise it. After a small movement ofthe piston If the the transverse boring 65 ceases to register with thechannels 67, so that the flow through to the throttle orifice isinterrupted. The pump, however, continues to discharge and thecontrolling piston 59 is therefore quickly forced upwardly until theborings 66 register with the channel 68 and thus open a return ow pathfor the fuel further discharged. The more the speed of rotation isincreased the more quickly will this return path be opened.

The control mechanism may be adjusted to allow sufficient fuel to passwithout lifting of the piston 59 to maintain a given engine speed.

In the eighth form of construction according to Figure 8 the shaft 74 ofthe spring-loaded valve 20 is guided in the manner of a piston, and isso formed that o-n return of the valve into its closed position itrelieves the pressure pipe. Moreover, the shaft 74 controls the returnflow of a portion of the fuel discharged by the pump 14 dependent uponthe discharge velocity. The loading of the valve spring 62 can beadjusted by the hand wheel 75. spindle 76, serving at thesame time as astop for the valve stroke displaces the spring-abutment plate 63,restrained in lateral grooves 77 against rotation therewith.

Formed in the shaft of the valve 20 is a longitudinal boring '78.Inclined channels 79 lead from the inner end of the longitudinal boring78 to an annular groove 80, formed in the shaft. In the inlet end of theshaft is a plug 81 having y a throttle orifice 82 formed therein. Aftera certain lift of the valve a transverse boring 83 in the guiding shaftthereof connects the longitudinal boring with a return flow channel 84.

The method of operation of this eighth form of construction will beunderstood from what has been stated in reference to the two precedingexamples. It has also been described in detail with reference to thethird example how the change of tension of the spring acting on thecontrolling member, which in the present case is the forcing valvespring 62, changes the maximum engine speed.

Instead of adjusting the engine speed by varying the loading of thespring, it may also be influenced by varying the stroke or movement ofthe valve necessary for effecting return of discharged fuel or byadjusting or altering the throttle orifice which causes a pressure dropthus effecting movement of the control piston. This pressure drop couldalso be produced by a Venturi tube instead of a throttle. One means ofobtaining a low degree of irregularity in the present control mechanismis to so form the driving cams that over the portion of the stroke inwhich the regulation is to be effected, the discharge velocity remainsalmost constant.

In all the forms of construction described the movable adjusting memberis formed as a piston valve. Instead of this valve a diaphragm could inmany cases be used. Within the scope of the invention many modificationscan be made of the examples described which only relate to internalcombustion engines having a fuel pump for each motor cylinder. Theregulating means described can also be used for other types of motorsfor example for blast air injection motors. ,The idea of the inventionis applicable to all fuel discharging members, in which the velocity ofthe fluid increases with the speed of rotation.

I claim: y

1. A fuel supply and regulating system for intemal combustion enginescomprising in combi- By rotating the hand Wheel, the screw nation atleast one pump chamber, a. piston within said chamber rotatable aboutits longitudinal axis for varying the effective discharge thereof,actuating` means for rotating said piston, a spring loaded pistonadapted to be connected with the discharge side of said pump chambergoverning said actuating means and a spring loaded piston valve having afuel passage therethrough and a throttle orifice at the inlet end of thepassage for controlling the connection of the spring loaded piston withthe pump chamber.

, 2. A fuel supply and regulating system for internal combustion enginescomprising in combination a fuel pump, a discharge duct from said pumpto an engine, an inlet duct to said pump from a fuel supply, a by-passfrom said discharge duct to the fuel supply and a spring loadedpistonValve sliding in said discharge duct, having a fuel passage therethroughleading to the engine and a throttle orifice at the inlet end of thepassage for controlling said by-pass.

3. A fuel supply and regulating system for an internal combustion enginecomprising in combination a fuel pump operated by said engine, a

fuel supply line connecting a source of fuel to said engine through saidpump, a throttling device located in said supply line on the dischargeside of said pump, and means comprising a bypass opening from saidsupply line on the discharge side of said pump between said throttlingdevice and the engine and leading to said supply line on the intake sideof said pump and a valve member in said supply line on the dischargeside of said pump movable over said by-pass opening in response to thepressure drop produced by said throttling device to control the amountof fuel delivered to said engine, said valve member having one faceexposed with said throttling device to the full discharge pressure ofsaid pump and another face exposed to the pressure in said delivery ducton the engine side of said throttling device.

4. A fuel supply and regulating system for an internal combustionenginecomprising in combination, a fuel pump positively driven by saidengine so that the velocity of discharge of fuel from said pump variesdirectly as the engine speed, a fuel delivery duct from said pump tosaid engine and means for controlling the quantity of. fuel delivered tothe engine comprising a by-pass opening from said delivery duct andleading to the intake side of said pump and a piston valve located insaid fuel delivery duct and operating over said by-pass opening tocontrol the discharge of fuel through said by-pass, said piston valvehaving a throttling aperture formed therein leading to the engine andthrough which the fuel flows, whereby said valve is operated inaccordance with the pressure difference developed in said fuel deliveryduct on the two sides of the piston. I

5. A fuel supply and regulating system for an internal combustion enginecomprising, in combination, a fuel pump positively driven vby saidenginewhereby the velocity of discharge of said pump varies directly with theengine speed, a fuel delivery duct leading from the discharge side ofAsaid pump to said engine, a by-pass opening from said fuel deliveryduct and leading to the intake side of said pump, a pressure-operatedvalve mov- .full discharge pressure of said pump and another faceexposed to the pressure in said delivery duet on the engine side-of saidthrottling device.

6. A fuel supply and regulating system for an internal combustion enginecomprising, in combination, a fuel pump positively driven by said enginewhereby the velocity of discharge of said pump varies directly with theengine speed, a fuel delivery duct leading from the discharge side ofsaid pump to said engine, and means for controlling the amount of fueldelivered to said engine comprising a by-pass opening from said fueldelivery duct and leading to the intake side of said pump, a loadedelement in said duct movable by the pressure thereagainst oi fueldischarged from said pump and having a Valve portion operating over saidby-pass opening to control said by-pass, a passage for the flow of fuelthrough said element from said pump to said engine and a throttlingrestriction at the entrance to -said passage operative to so increasethe fuel pressure on said element as the engine speed and consequentdischarge of fuel from said pump increases as to move said elementagainst itsv load to an extent opening said by-pass when a predeterminedengine speed has been reached.

7. A fuel supply and regulating system for an internal combustion enginecomprising, in combination, a fuel pump positively driven by said enginewhereby the velocity of discharge of said pump varies directly with theengine speed, a discharge duct from said pump to said engine, a bypassfor fuel from the discharge side .to the intakev side of said pump, andmeans for closing said bypass up to a predetermined engine speed andthereafter opening the -same comprising a pressure-operated valve memberlocated and movable insaid discharge duct and having one face exposed tothe pressure in said discharge duct on the engine side of said memberand a loading tending to move said member in a direction effectingclosure of said by-pass, said valve member having an opposite faceexposed to the pressure created by said pump on its discharge stroke, aduct connecting said opposite faces of said valve member upon thedischarge stroke of said pump and a throttling restriction in said ductoperative to produce such a pressure difference on said opposite facesof said valve member at a predetermined speed of said engine andcorresponding velocity of discharge of fuel from said pump as to movesaid valve member against its load suiciently to open said by-pass. Y

8. A fuel supply and -regulating system as dened in claim 7 and whichsaid duct connecting said opposite faces of said valve member is formedin said valve member itself.

9. A fuel supply and regulating system for an internal combustion enginecomprising, in combination, a fuel pump positively driven by said enginewhereby the velocity of discharge of said pump varies directly with theengine speed, a discharge duct from` said pump to said engine, a by-passfor fuel opening from said discharge duct and leading to the intake sideof said pump, a pressure-operated valve member located and movable insaid discharge duct oversaid by-pass opening to control said by-pass,said valve member having an end surface exposed to the pressure in saiddischarge duct on the engine side of said by-pass opening and a loadingtending' to move said member in a direction effecting closure of saidby-pass, said valve member hav` ing an opposite end surface on the pumpside of said by-pass opening exposed to the pressure created by the pumpon its discharge stroke, a duct connecting said opposite end surfaces ofsaid f valve member upon the discharge stroke 'of said pump and athrottling restriction in said duct on the pump side of said by-passopening operating in response to changes in velocity of the total fueldischarge from said pump to effect such a pressure difference on saidopposite end surfaces of said valve member as to maintain said valvemember in position closing said by-pass until a predetermined enginespeed and corresponding velocity of fuel discharge from said pump hasbeen reached and then to move said valve member sufficiently to opensaid by-pass.

10. A fuel supply and regulating system for an internal combustionengine comprising, in combination, a fuel pump positively driven by saidengine whereby the velocity of discharge of said pump Varies directlywith the engine speed, a discharge'duct from said pump to said engine, aby-pass for 4fuel from the discharge side to the intake side of saidpump, a pressure-operated discharge valve for said pump having a linearmovement in said duct, said valve Ahaving a passage through its bodyformed with a throttling restriction at the inletl end on the pump sideof the valve arranged for the flow therethrough in the open position ofsaid valve of fuel from said pump to said engine, saidpassage andthrottling restriction in said valve being of such dimensions for theflow of fuel therethrough and said valve having such a loading as tovary the length of stroke of the valve in the opening direction directlywith the velocity of discharge of fuel from said pump consequent uponthe speed of said engine, a valve for controlling said by-pass and amechanical connection between said valves whereby said discharge valvemaintains said by-pass valve closed until said discharge valve hasadvanced a predetermined distance in its opening direction less than thefull length of its opening stroke and then effects the opening of saidby-pass valve.

11. A fuel supply and regulating system for an internal combustionengine comprising, in combination, a fuel pump positively driven by saidengine whereby the velocity of discharge of said pump varies directlywith the engine speed, a discharge duct from said pump to said engine, aby-pass for fuel opening from said discharge duct and leading to theintake side of said pump, a non-return discharge valve in said dischargeduct on the engine side of said by-pass opening having a skirt portionextending therefrom toward the pump and movable over said by-passopening to maintain said by-pass closed until said discharge valve hasmoved a predetermined distance in opening direction less than the fulllength of its opening stroke and then to open bination, a fuel pumppositively driven by said engine whereby the velocity of discharge ofsaid pump varies directly with the engine speed, a discharge duct fromsaid pump to said engine, a by-pass for fuel opening from said dischargeduct and leading to the intake side of said pump, a pressure-operatedpiston valve located and movable in said discharge duct over saidby-pass opening to control said by-pass, said piston valve having oneend face in said discharge duct on the engine side of said by-passopening and a loading tending to move said valve in a direction closingVsaid by-pass and an opposite end face on the pump side of said by-passopening exposed to the pressure created by said pump on its dischargestroke, said valve having a duct connecting said opposite end faces uponthe discharge stroke of said pump and a throttling restriction in saidduct on the pump side of said by-pass opening' adapted to produce suchra. pressure difference on said opposite faces of said valve at apredetermined speed of said engine and corresponding velocity ofdischarge of fuel from said pump as to move said valve against its loadsufciently to open said by-pass.

13.l A fuel supply and regulating system for an internal combustionengine comprising, in combination, a fuel pump positively driven by saidengine whereby the velocity of discharge of said pump varies directlywith the engine speed, a discharge duct from said pump leading to saidengine, an annular valve seat in said duct, a bypass for fuel openingfrom said discharge duct on the pump side of said valve seat and leadingto the intake side of said pump, a pressureoperated piston body slidablymounted in said discharge duct and having a head portion forming anon-return discharge valve movable from and into engagement with saidvalve seat on the engine side thereof to control the delivery of fuelfrom said pump to said engine, said piston body having a rear portion onthe pump side of said by-pass opening always exposed to the fulldelivery pressure of said pump and an axial passage therethrough with athrottling restriction at its inlet end and an outlet rearwardlyadjacent said non-return valve in position to be closed when said valveengages said valve seat and to be opened for the ow of fuel therethroughand past said valve to the engine when said valve moves from saidseatiand an intermediate aper- ,tured portion formed to maintain saidby-pass closed until said discharge valve advances a predetermineddistance in its opening direction and then to open said by-pass.

MAX HURST.

